Last weekend I went furniture shopping with one of my friends. We went to a wide array of stores. The furniture exhibited on the floor varied from antique, oversized pieces to clean, modern looks. I thought the options would never end. And, after a while, it all started to look the same until an exquisite, large metal table caught my eye. It looked like a seamless piece of steel that must have been welded together. Well, the welding aspect sparked my interest. I thought how do designers weld together metal. Are there different types of welding? Here is what I found out.
Most welding methods use heat to join two or more pieces of metal together. In explosion, there is no heat applied. Instead, the process relies upon a high energy collision and movement. For example, a shock wave could provide enough heat from the power of the impact and the energy exhausted brings the pieces of metal together. This technique is used when producing heat exchangers and repairing leak tube-to-tube sheet joints.
The cold technique is when you take material and connect them by using high pressure at room temperature or a vacuum without heat. Unlike other practices, there is no liquefied state present. You are able to use handheld tools or a large press for sizable objects.
Inertia is a type of friction welding that involves a spinning flywheel being rotated by a motor until a certain speed is achieved. Once this occurs, the other piece (or pieces) to be welded rotates, the motor disengages from the flywheel and the welded part joins on contact the rotating piece. The contact moment is when pressure is applied and action takes place. At the moment the flywheel slows down or completely stops, more pressure is applied and the welding is finished.
Hammer is also known as forge. This process includes joining metals by heating them in an oven and applying weight or whacks powerful enough to create long-lasting distortion at the crossing point. When imagining this welding, think about a blacksmith doing his/her work. A blacksmith uses the same process.
Roll and hammer welding are very similar. They both use pressure to connect the two metals. The only difference is with roll welding, hammering does not occur. It uses pressure caused by a rolling motion. It is one of the most common procedures utilized in casing low alloy steel with stainless steel.